[Reprinted from PSYCHE. Vol. XXXIX. No. 3 (1 932)]
VOL. XXXIX SEPTEMBER, 1932 No. 3
AN AUSTRALIAN LEPTANILLA
By William Morton Wheeler
The very interesting Formicid subfamily Leptanillinae
comprises only two genera of minute, yellow, blind and
hypogseic ants, namely, Leptanilla, established by Emery
as long ago as 1870 and Phaulomyrma, established by G. C.
and E. W. Wheeler in 1930 on a male specimen from
Java. This genus probably also includes Santschi's L. tanit
from Tunis. Of the eleven described species of Leptanilla,
four are known only from males; of the remaining seven,
five are known only from workers and only two from both
workers and females. The geographical distribution of the
various species is peculiar. Six of them, namely, L. theryi
Forel, vaucheri Emery, exigua Santschi, minuscula Sants-
chi, nana Santschi and tenuis Santschi, were taken in
North Africa (Algiers, Tunis, Morocco), two, doderoi Em-
ery and revelierei Emery, in Corsica and Sardinia (though
the subspecies chohawti Emery of revelierei occurs in Mo-
rocco), two, havilandi Forel and butteli Forel, in the Malay
Peninsula and one, santschii G. C. and E. W. Wheeler, in
During November, 1931, while I was with the Harvard
Zoological Expedition in Australia, Mr. D. C. Swan of the
Waite Institute at Glen Osmond, S. A., generously gave me
some minute ants which he discovered in Western Austra-
54 Psyche [September
lia. The collection comprises two dozen workers, a female
and a number of full-grown larvae, which prove to belong
to an undescribed species of Leptanilla. They therefore
considerably extend the known geographical range of the
genus. Owing to the fact that the Leptanillinse are true
members of Silvestri's "microgenton" and that their work-
ers and females are very rarely seen, because they come to
the surface of the soil only under unusual conditions, such
as excessive rainfall, it is too early to regard the various
species at present known as covering the entire range of
the genus. We should expect careful collecting with the
Berlese funnel to bring additional forms to light in South
Africa, Madagascar, Asia Minor and India, or even, per-
haps, in the warmer parts of the New World.
Leptanilla swani sp. nov.
Worker. (Fig. 1, a-d.) Length 1.3-1.5 mm. Pale yellowy
legs scarcely paler than the body ; teeth and borders of the
Head flattened above, oblong, fully li/^ times as long as
broad, as broad in front as behind, with subparallel sides,
rounded posterior corners and feebly concave posterior
border. Mandibles narrow, with very oblique 4-toothed
apical borders, the terminal tooth curved and acute, the
second minute, the two remaining teeth stout and rather
blunt, the most basal directed at right angles to the apical
border or even slightly backward. Clypeus without distinct
posterior suture, its anterior border slightly but distinctly
produced in the middle as a broadly rounded lobe, excised
at the sides. Antennae moderately stout; scapes reaching
nearly to the middle of the head; basal funicular joint
nearly li/^ times as long as broad, ovoidal, with constricted
base; joints 2-6 distinctly broader than long; the second
basally constricted, the seventh distinctly longer, 8-10 as
broad as long, the terminal joint as long as the two preced-
ing joints together. Thorax much narrower than the head
including the mandibles, flattened dorsally and not deeply
notched in profile at the promesonotal suture; pronotum
subovoidal, somewhat broader than the mesepinotum, which
is longer than the pronotum, with feebly rounded, sub-
parallel sides. Petiole much narrower than the epinotum.
An Australian Leptanilla
nearly II/2 times as long as broad, gradually narrowed an-
teriorly, posteriorly with rounded-subparallel sides. Post-
petiole rounded-trapezoidal, nearly as long as broad, some-
what broader than the petiole and somewhat wider behind
than in front, its ventral surface convex and projecting.
Gaster narrow, elongate-elliptical, anterior border of first
segment slightly concave. Sting large, retracted. Legs mod-
FlG. 1. Leptanilla sivani sp. nov. a, worker; b, clypens and mandible
of same; c, antenna; d, fore tibia and tarsus; e, female;
/, clypeus and mandible of same.
erately stout, tips of fore metatarsi produced and digiti-
form, but not so narrowly as in L. narm Santschi.
Shining, with very fine and indistinct piligerous punc-
tures. Pilosity white, very short, abundant both on the
body and antennse, slightly longer and coarser on the gaster,
less conspicuous and more dilute and appressed on the legs.
Female. (Fig. 1, e and f.) Length 2 mm.
Color, sculpture and pilosity as in the worker, but the
hairs on the gaster very long, though fine, as in the female
of L. theryi Forel.
56 Psyche [September
Apterous and resembling the worker in form but differing
in the following characters : Head more sharply oblong,
with straight and more clearly parallel sides. Mandibles
falcate, narrow and tapering at the tips, without distinct
basal and apical borders, terminating in two small, indis-
tinct, closely approximated teeth. Clypeus broader and less
produced than in the worker. Thorax decidedly longer than
the head plus the mandibles, very low and flat above, the
pronotum posteriorly nearly as broad as the head, longer
than broad, with feebly rounded, anteriorly converging
sides, mesepinotum broader than the head, subtrapezoidal,
broadest near the anterior end, roundly subtruncate behind.
Promesonotal suture pronounced, straight and transverse
in the middle. Petiole regularly oblong, about I14 longer
than broad, as broad in front as behind. Gaster much
larger than in the worker, the postpetiole, which forms its
first segment, nearly twice as broad as long, subtrape-
zoidal, with straight anterior border. Genitalia similar to
those of L. revelierei Emery, but the pygidium with entire,
broadly and semicircularly rounded posterior border, not
notched in the middle. Hypopygium large, narrowed and
bluntly bidentate posteriorly. Legs longer and stouter than
in the worker.
Described from 24 workers and a single female taken
Oct. 10, 1931 by Mr. D. C. Swan under a large stone at
Goyamin Pool, Chittering, Western Australia.
L. swani seems to be most closely related to L. revelierei,
but the female of the latter has a much shorter petiole. In
the long pilosity of the gaster the female of the new form
resembles theryi, but in this species the petiole is very
different, being distinctly cordate anteriorly instead of
Dr. G. C. Wheeler, to whom I sent the larvae of L. swani
for study, writes me that he found them "extremely inter-
esting because of their close resemblance to the larvae of
revelieri subsp. sardoa. They even have the 'tympanum'
which is difficult to detect unless the specimens are stained.
This species differs from sardoa in the following charac-
teristics: (1) The head is sharply constricted just in front
of the middle so that in dorsal view it is flask-shaped or key-
hole shaped ; the posterior half is circular, the middle half
1932] An Aiistralian Leptanilla 57
is about half as wide and has subparallel sides. (2)^The
prothorax is sparsely spinulose while the curious structure
oji its ventral surface has its base densely and coarsely
spinulose. (3) The two extremely long hairs at the poste-
rior end are lacking in all specimens."
Emery, as is well known, regarded the Leptanillinse as
constituting a special tribe of the Dorylinse, but Dr. G. C.
Wheeler and I have raised the group to subfamily rank.
Unquestionably, Emery, in his paper of 1904, based his
opinion very largely on the singular characters of the fe-
male, which he regarded as a true dichthadiigyne and com-
pared with the female of Aenictus. Strangely enough, Em-
ery seems not to have noticed the peculiar falcate shape of
the female mandibles, so unlike those of the worker, a char-
acter which, taken together with the absence of wings and
the single segment of the pedicel, makes the resemblance to
the females of the Dorylinse even greater than he supposed.
But the males of the Leptanillinse and the larvse, as described
and figured by G. C. Wheeler, are so very unlike those of the
Dorylinse that we are bound to regard the striking similari-
ties of the females as due to convergence. Emery's original
interpretation of the thoracic segmentation of the female
Leptanilla was incorrect, because he regarded the portion
of the thorax anterior to the pronounced transverse dorsal
suture as the mesonotum, the portion posterior to the suture
as the combined metanotum and epinotum. In a foot-note
to his section on the Leptanillinse in the "Genera Insecto-
rum" (1910), he recognized his error and adopted the in-
terpretation which I have also reached, namely, that the
presutural portion is the pronotum, the postsutural the com-
bined meso- and epinotum.
The occurrence of indigenous species of Leptanilla on is-
lands like Corsica, Sardinia, Java and Australia is signifi-
cant. Since the females are apterous and obviously too
small and delicate to endure distant transportation in flot-
sam and jetsom, we must suppose that they have occupied
their present habitats since the islands mentioned were
connected with the mainland. The Leptanillinse, therefore,
must be very ancient, like many other components of the
microgenton (Kcenenia, Pauropus, Scolopendrella, Cam-
podea, lapyx, etc.) L. swani is particularly interesting in
58 Psyche [September
this connection, because the extreme southwestern corner of
Australia, in which it was taken, is known to possess the
oldest and least disturbed fauna of any portion of the con-
Emerif, C. Studi Mirmecologici. Bull. Soc. Ent. Ital. 2, 1870, pp. 193-
201, 1 pi.
Emery, C. Le affinita del genera DeptanlUa e i limiti delle Dorylinse.
Archiv. Zool. Ital. 2, 1904, pp. 107-116, 9 figs.
Emery, C. Pormicidae, subfam. Dorylinse, in Wytsman's Genera In-
sectorum, 1910, pp. 32-33.
Wheeler, a. 0. The Larva of Leptanilla. Psyche 35, 1928, pp. 85-91,
Wheeler, G. G. and E. W. Two New Ants from Java. Psyche 37, 1930,
pp. 193-201, 2 figs.